In the practice of orthodontia, corrective forces are applied to the teeth so as to reposition them in a desired configuration. A typical orthodontic appliance system generally comprises a plurality of orthodontic brackets which are individually secured to the teeth, and an orthodontic arch wire secured to the brackets such that corrective forces are applied to the teeth. In order to transmit the appropriate force necessary to reposition the teeth, the orthodontic archwires have been typically made of metal.
Recently, in the field of orthodontia, it has been increasingly important to provide an asthetically pleasing orthodontic applicance system. As a result, orthodontic brackets made of a substantially transparent, translucent or tooth colored material have become very popular, for example, orthodontic brackets made of single or polycrystalline material, or of a ceramic material having a color substantially the same as the teeth. While these brackets have provided an improved aesthetic appearance, the arch wire is still quite visible. It has been suggested that orthodontic arch wires have an inner metal core and an outer plastic wire which can be colored so as to make it less obtrusive. An example of such orthodontic arch wires are illustrated in U.S. Pat. No. 4,659,310 and U.S. Pat. No. 4,585,414. The problem with such products is that they are opaque subject to staining, and due to the additional outer plastic layer, the size becomes greater. Another problem with such arch wires is its ability to provide the strength necessary to transmit the required corrective forces and still be relatively small in size. It has also been suggested to use fiber-reinforced composite materials for orthodontic brackets, such as illustrated in U.S. Pat. No. 4,717,341. Here again, the problem with such prior art devices is its ability to provide the appropriate strength in a relatively small size wire and the problem of staining.
Applicants have developed an orthodontic appliance system which includes an orthodontic arch wire which has an improved aesthetic appearance, and has the strength necessary to operate as an orthodontic archwire.